We propose studies on the fate of natural C19-steroids in explants of immature, mature and regressed canine prostate and epididymis and human prostatic adenoma and adenocarcinoma, structurally maintained in serum-free medium. Our overall objective is to attribute effects on epithelial structure and biochemical functions to testosterone and its intracellular metabolites. Effects of inhibitors of C19-steroid metabolism and high-affinity 5-alpha-dihydrotestosterone binding on organ-culture disposition of the selected substrate will be investigated. Evaluation of the response of explants with immature or retrogressed epithelium to the androgen supplement will be by morphometric assessment of gross and fine structure, assay of cytoplasmic androgen receptor and determination of the activities and isozyme patterns of prostatic acid phosphatase and epididymal alpha-mannosidase.